Casio CTK-900 Personal Computer User Manual


 
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19.3 Handshake Protocol Communication Flow
A session starts with the receiving device sending a request using an HDR or with the sending device sending
HDS data.
The sending device does not send the next packet until it receives an ACK from the receiving device. The
maximum wait time of at least 2000 msec is reserved. Failure of a response to arrive within the wait time (at
least 2000 msec) is treated as a timeout error, and data communication is terminated.
The sending device resends the last data if the receiving device returns an HDE (error) due to checksum mismatch,
incompatible data structure, or some other reason. If an error repeats a number of times (undefined), either the
sending device or the receiving device sends an HDJ to terminate the session.
A session ends after the sending device sends all the parameter sets, and sends a final EOD in response to an
HAD (ACK) from the sending device.
The same packet is resent when a checksum mismatch or incompatible data structure error is detected.
Data send is canceled when no acknowledgement (ACK) is received.
Data Receiver Data Sender Operation
HDR Send Request (Optional)
HDS Data Send
HDA Acknowledge
HDS Data Send
HDA Acknowledge
:
:
HDA Acknowledge
EOD Data End
:
Other subsessions
:
EOS End of session
Data Receiver Data Sender Operation
HDR Send Request (Optional)
HDS Data Send
HDA Acknowledge
HDS Data Send
HDE Error
HDS Data Resend
:
:
HDE Error
EOD Data End
:
Other subsessions
:
EOS End of session